1. Field of the Invention
This invention relates to wireless networking and more particularly to mitigating data rate degradation of wireless communications between a wireless access point and a wireless client.
2. Description of the Related Art
Wireless local area networks (WLANs) are being established throughout the world to allow users to connect to a network or to the Internet via a network. Schools, businesses, governments, and even individuals are setting up wireless networks that allow multiple users to access a wireless network using laptop computers, personal digital assistants (PDAs), workstations, printers, and many other networking devices. Additionally, many of these wireless networks are available indoors and outdoors, making it possible to connect to a wireless network in virtually any location.
Conventional wireless networks are typically implemented using an international wireless standard established by the Institute of Electrical and Electronic Engineers (IEEE). The standard, IEEE 802.11, defines various transmission protocols that may be employed to transmit network information via a wireless local area network. Generally, the IEEE 802.11 standard is implemented in the 2.45 GHz industrial, scientific and medical (ISM) band that is between 2.4 and 2.5 GHz. Other ISM bands, such as around 5.8 GHz, may also be used.
Within the 2.45 GHz ISM band, multiple channels are designated for WLAN transmissions. The 802.11b specification allows up to 14 channels. For example, the United States and Canada use 11 channels. In contrast, Japan uses 14 channels. The channels are defined between 2.412 and 2.477 GHz in 5 MHz increments, as indicated in Table 1.
TABLE 1802.11b ChannelsChannelFrequency12.41222.41732.42242.42752.43262.43772.44282.44792.452102.457112.462122.467132.472142.477
In most instances, a wireless local area network (WLAN) includes a network server communicating with a wireless access point. The wireless access point is typically hardwired to the network server, using, for instance, twisted-pair, coaxial, or fiber optic cables. The wireless access point is configured to communicate with one or more wireless client devices, such a laptop computers, PDAs, and so forth, allowing the wireless client devices to access the network. The main function of the wireless access point is to form a bridge between the wireless client devices and the hard-wired network.
In order to communicate with the wireless client devices, the wireless access point operates on a single channel. The channel may be selected by a network administrator, for example, when the wireless network is set up or may be set to a default channel. Once a channel is selected and a wireless access point is available for network communications, the wireless access point transmits a beacon that identifies the wireless access point to potential wireless client devices. The wireless client devices then scan the available channels to determine which channel is being used by a specific wireless access point as indicated by the beacon. Once a wireless client device finds a suitable wireless access point (one with which the wireless client device can and wants to communicate), a wireless network connection may be established between the wireless access point and the wireless client device.
Unfortunately, as the number of wireless local area networks (WLANs) increases and the transmission coverage area of WLANs continues to grow, the amount of interference on a given WLAN may also increase. Interference on a WLAN may be due to several interference sources, including disparate wireless access points operating in close physical proximity to one another, electrical current sources and transmission mediums, and other transmission devices operating within the channels and nearby frequencies. For example, cellular telephones and microwave ovens may cause interference on a particular WLAN and cause the data rate of the WLAN to decrease because of packet losses and retransmissions. Wireless client devices operating on the same channel or adjacent channels also may cause the data rate for one or both WLANs to decrease. Interference caused by separate devices operating on adjacent channels may be referred to as co-channel interference or signal overlap bleeding.
What is needed is a process, apparatus, and system that mitigates data rate degradation of wireless communications between a wireless access point and a wireless client. Beneficially, such a process, apparatus, and system would assess the quality of wireless communications between a wireless access point and a wireless client and facilitate communications between the wireless access point and the wireless client using a best communications channel—the channel having the least known interference, if any.